The quality of a musical performance out of doors is diminished if a background sound reflecting structure is not employed to direct the sound toward the listening audience. Portable sound enhancing panel structures are known to amplify and project sound from bands, orchestras or choral performers outwardly toward a listening audience. The panel structure when used for outdoor performances capture and redirect the upwardly directed sound back to the performers and forward to the listening audience. An example of a portable acoustic panel structure, disclosed by J. C. Jaffe in U.S. Pat. No. 3,232,370, has panels hinged together to provide an upright shell. Upright legs connected to wheels support the panels above a floor. The prior art acoustic shells are complex structures which are heavy and awkward to move around once they are assembled. Casters and wheels used to roll the shells to selected locations on hard surfaces are unsuitable for outdoor use on soft ground and grass lawns. There is a need for a portable, low cost and lightweight acoustic panel assembly that is adapted for use in outdoor locations.